Rank the following complex ions in order of increasing wavelength of light absorbed. (Use the appropriate <, =, or > symbol to separate substances in the list.)
Co(H2O)63+, Co(CN)63-, CoI63-, Co(en)33+
Fxs
To determine the order of increasing wavelength of light absorbed for the given complex ions, we need to consider the ligand and its effect on the metal ion's electronic structure. Generally, ligands can be classified as weak field ligands or strong field ligands, based on their ability to split the d-orbitals of the metal ion.
The ligands in the given complex ions can be ranked in terms of their crystal field strength as follows:
en (ethylenediamine) > H2O (water) > CN- (cyanide) > I- (iodide)
Strong field ligands, such as en, cause a larger energy difference between the d-orbitals, resulting in the absorption of light of higher energy (shorter wavelength). On the other hand, weak field ligands, like I-, produce smaller energy differences between the d-orbitals, leading to the absorption of light of lower energy (longer wavelength).
Based on this information, we can rank the complex ions in order of increasing wavelength of light absorbed:
CoI63- > Co(CN)63- > Co(H2O)63+ > Co(en)33+
Alternatively, we can say:
Co(en)33+ < Co(H2O)63+ < Co(CN)63- < CoI63-